It has been found necessary to install substantially rigid but somewhat flexible plastic foam insulation panels or sheets about a wide diameter pipeline. The sheet wrapper had to be simple and sturdy in construction with a minimum of moving parts so that it could be used repeatedly without breakdown, and yet maintain a reasonably high degree of accuracy in properly placing of the insulation panels about sections of the pipeline. To accomplish this the present sheet wrapper was designed such that its weight is utilized to perform the mechanical work of wrapping the insulation panels about pipe sections. The sheet wrapper provides reliability and simple functionality by means of a plurality of yoke assemblies which cover the insulation panels about the pipe circumference. As each insulation panel is wrapped about the pipe it is secured together at its free ends, and the yoke assemblies are removed.